
Hi
I used to be with Freeserve/Wanadoo/Orange (they keep changing their name!) and they do have a rule that they de-activate your account if you do not sign in to it using THEIR dial up (or their broadband) at least once every 30 or 60 days-can't remember which now. You probably also will not be able to send e-mails using another smtp than their own, and can only use their smtp when connected to them.
If you just want to sign in to check your e-mails, you can quite easily install them as a second dial up account (and pay per minute when you are connected to them) and just connect to that instead of talk talk, that's no problem. You can have any number of dial up connections on your computer.